Bfp Calculator

Body Fat Percentage (BFP) Calculator

Male Female

Your Estimated Body Fat Percentage:

0%

Category

function calculateBFP() { var gender = document.getElementById('bfp_gender').value; var age = parseFloat(document.getElementById('bfp_age').value); var heightCm = parseFloat(document.getElementById('bfp_height').value); var weightKg = parseFloat(document.getElementById('bfp_weight').value); if (isNaN(age) || isNaN(heightCm) || isNaN(weightKg) || age <= 0 || heightCm <= 0 || weightKg <= 0) { alert('Please enter valid positive numbers for all fields.'); return; } var heightMeters = heightCm / 100; var bmi = weightKg / (heightMeters * heightMeters); var bfp = 0; var genderVal = (gender === 'male') ? 1 : 0; // Adult Body Fat Percentage Formula (Deurenberg et al.) // BFP = (1.20 × BMI) + (0.23 × Age) – (10.8 × gender) – 5.4 // where gender: male = 1, female = 0 bfp = (1.20 * bmi) + (0.23 * age) – (10.8 * genderVal) – 5.4; if (bfp < 2) bfp = 2; // Floor for physical possibility var resultContainer = document.getElementById('bfp_result_container'); var valDisplay = document.getElementById('bfp_final_val'); var catDisplay = document.getElementById('bfp_category'); valDisplay.innerHTML = bfp.toFixed(1) + '%'; var category = ""; if (gender === 'male') { if (bfp < 6) category = "Essential Fat"; else if (bfp < 14) category = "Athletes"; else if (bfp < 18) category = "Fitness"; else if (bfp < 25) category = "Average"; else category = "Obese"; } else { if (bfp < 14) category = "Essential Fat"; else if (bfp < 21) category = "Athletes"; else if (bfp < 25) category = "Fitness"; else if (bfp < 32) category = "Average"; else category = "Obese"; } catDisplay.innerHTML = category; resultContainer.style.display = 'block'; }

While most people rely on the number on the scale to track their health progress, weight alone doesn't tell the whole story. Body Fat Percentage (BFP) is a much more accurate metric for assessing physical fitness and health risks because it distinguishes between muscle mass and fat mass.

What is Body Fat Percentage?

Body fat percentage is the total mass of fat divided by total body mass, multiplied by 100. Body fat includes essential body fat (necessary for life and reproductive functions) and storage body fat (fat tissue that protects internal organs and stores energy).

Calculation Method Used

Our BFP calculator uses the BMI-based formula developed by Deurenberg. It considers your Body Mass Index (BMI), age, and biological sex to estimate fat content. While clinical methods like DEXA scans or hydrostatic weighing are more precise, this formula provides a reliable estimate for the average person without requiring specialized equipment.

Healthy Body Fat Ranges

Ideal body fat levels vary significantly between men and women due to hormonal differences and physiological requirements (such as childbirth for women).

Category	Women (%)	Men (%)
Essential Fat	10–13%	2–5%
Athletes	14–20%	6–13%
Fitness	21–24%	14–17%
Average	25–31%	18–24%
Obese	32%+	25%+

Practical Examples

To understand how the variables interact, consider these scenarios:

• Example 1: A 30-year-old male, 180cm tall and weighing 85kg. His BMI is 26.2. Using the formula, his estimated body fat is approximately 21.3%, placing him in the "Average" category.
• Example 2: A 25-year-old female, 165cm tall and weighing 55kg. Her BMI is 20.2. Her estimated body fat is roughly 24.6%, placing her in the "Fitness/Average" threshold.

Why Track Body Fat Instead of Weight?

Focusing purely on weight can be misleading. For instance, a bodybuilder may have a high BMI (indicating they are "overweight") while having very low body fat. Conversely, a "skinny fat" person might have a normal weight but high body fat levels, which poses metabolic health risks like Type 2 diabetes and hypertension.

Important Considerations

This calculator is a screening tool and has limitations:

1. Muscle Mass: It may overestimate body fat in highly muscular individuals.
2. Age: As we age, our body density changes; the formula accounts for this but remains an estimate.
3. Hydration: While this mathematical formula doesn't change with water weight, physical measurements (like bioelectrical impedance scales) often do.